Different infective forms trigger distinct immune response in experimental Chagas disease

Area of Science:

• Immunology
• Parasitology
• Infectious Diseases

Background:

• Metacyclic trypomastigotes (MT) and blood trypomastigotes (BT) of *T. cruzi* differ in surface molecules, influencing host cell interactions.
• These molecular differences may significantly affect the immune response and clinical outcomes in Chagas disease.

Purpose of the Study:

• To investigate how infection with MT versus BT forms of *T. cruzi* influences the acute phase immune response and cardiac inflammation.
• To elucidate the distinct parasite-host interactions triggered by different infection routes.

Main Methods:

• Mice were infected with either MT or BT forms of *T. cruzi*.
• Parasitemia, leukocyte counts (total leukocytes, monocytes, lymphocytes), pro-inflammatory cytokine production (TNF-α, IFN-γ), and cardiac inflammation were monitored during the acute infection phase.

Main Results:

• BT infection led to higher parasitemia and earlier increases in leukocytes, TNF-α, and cardiac inflammation compared to MT infection.
• MT infection induced an earlier IFN-γ response, later modulated by IL-10, resulting in a distinct cardiac inflammation profile.
• Distinct T cell subpopulation responses and cytokine profiles were observed between MT and BT infections.

Conclusions:

• The source of *T. cruzi* inoculum (MT vs. BT) significantly shapes the acute phase immune response and parasite-host interactions.
• These early events have critical implications for the subsequent development and clinical manifestations of chronic Chagas disease.
• Considering the infective stage of *T. cruzi* is crucial for understanding Chagas disease pathogenesis.